Along with advancement of the integrated circuit technique, size of an integrated circuit is reduced and integration density is increased while function thereof is complicated. Reduced size, increased density and complicated function all mean increased heat generation per unit area.
Since a semiconductor chip contains extremely dense components, the operation frequency gets higher and the structure becomes more complicated, the heat generated may destroy the chip or degrade the lines thereof, resulting in reliability reduction or life time shortening, thereby increasing cost and causing damage.
Therefore, it is important to provide a heat sink to suppress operation temperature of a chip. In the case of BGA package, however, since the product is compact, it is fragile so that to externally provide a heat sink is considerably difficult. Besides, intensive care must be taken during the mounting process to avoid excessive cost and damage of the chip, which reduces yield thereof.